Peelable cable jacket having designed microstructures and methods for making peelable cable jackets having designed microstructures

ABSTRACT

Coated conductors include a conductor and a peelable polymeric coating at least partially surrounding the conductor, where the peelable polymeric coating includes from 1 to 8 microcapillaries that define individual, discrete void spaces. Also included herein are methods for making such coated conductors.

REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 62/233,620, filed on Sep. 28, 2015.

FIELD

Various embodiments of the present invention relate to cable coatingsand jackets having microcapillary structures which allow for ease ofpeeling.

INTRODUCTION

Cables often require access to their core for ease of connection andinstallation. Generally, cables are designed for maximum protection ofthe internal components, requiring the use of tough materials. As aresult, tearing the cable coating to access such internal componentsduring connection or installation is difficult. For instance, whenconnecting cables, a skilled installer must typically use sharp cuttingtools to split open the jacket and then use special tools to access thecable's internal components. The costs of network installation andsubsequent maintenance or cable replacement can be lowered by usage ofcables in which the inner components are easily accessible for ease ofconnection. While some attempts have been made to provide cable jacketswith easy access to internal components, such advancements often come atthe expense of the jackets' mechanical properties.

SUMMARY

One embodiment is a coated conductor, comprising:

-   -   (a) a conductor; and    -   (b) a peelable polymeric coating surrounding at least a portion        of said conductor,    -   wherein said peelable polymeric coating comprises a polymeric        matrix material and in the range of from 1 to 8 microcapillaries        which extend substantially in the direction of elongation of        said peelable polymeric coating,    -   wherein said microcapillaries define individual, discrete void        spaces.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the accompanying drawings in which:

FIG. 1 is a perspective view, partially in cross-section, of an extruderwith a die assembly for manufacturing a microcapillary film;

FIG. 2A is a longitudinal-sectional view of a microcapillary film;

FIGS. 2B and 2C are cross-sectional views of a microcapillary film;

FIG. 2D is an elevated view of a microcapillary film;

FIG. 2E is a segment 2E of a longitudinal sectional view of themicrocapillary film, as shown in FIG. 2B;

FIG. 2F is an exploded view of a microcapillary film;

FIG. 2G is a cross-sectional view of a microcapillary film particularlydepicting a single-layer embodiment;

FIGS. 3A and 3B are schematic perspective views of variousconfigurations of extruder assemblies including an annular die assemblyfor manufacturing coextruded multi-layer annular microcapillary productsand air-filled multi-layer annular microcapillary products,respectively;

FIG. 4A is a schematic view of a microcapillary film havingmicrocapillaries with a fluid therein;

FIG. 4B is a cross-sectional view of a coextruded microcapillary film;

FIG. 4C is a cross-sectional view of an inventive air-filledmicrocapillary film;

FIG. 5 is a schematic view of an annular microcapillary tubing extrudedfrom a die assembly;

FIGS. 6A and 6B are perspective views of an annular microcapillarytubing;

FIGS. 7A-7D are partial cross-sectional, longitudinal cross-sectional,end, and detailed cross-sectional views, respectively, of an annular dieassembly in an asymmetric flow configuration;

FIGS. 8A-8D are partial cross-sectional, longitudinal cross-sectional,end, and detailed cross-sectional views, respectively, of an annular dieassembly in a symmetric flow configuration;

FIGS. 9A-9D are partial cross-sectional, longitudinal cross-sectional,end, and detailed cross-sectional views, respectively, of an annular dieassembly in a symmetric flow configuration; and

FIG. 10 is a perspective view of a die insert for an annular dieassembly.

DETAILED DESCRIPTION

The present disclosure relates to die assemblies and extruders forproducing annular microcapillary products. Such annular microcapillaryproducts may be used in fabricating wire and cable articles ofmanufacture, such as by forming at least a portion of a polymericcoating (e.g., a jacket) or a polymeric protective component surroundinga conductive core.

The die assembly includes an annular die insert positioned betweenmanifolds and defining material flow channels therebetween for extrudinglayers of a thermoplastic material. The die insert has a tip havingmicrocapillary flow channels on an outer surface for insertion ofmicrocapillary material in microcapillaries between the extruded layersof thermoplastic material. The microcapillaries may contain a variety ofmaterials, such as other thermoplastic materials or elastomericmaterials, or may simply be void-space microcapillaries (i.e.,containing a gas, such as air). The die assemblies for producing annularmicrocapillary products are a variation of die assemblies for producingmicrocapillary films, both described in detail, below.

Microcapillary Film Extruder

FIG. 1 depicts an example extruder (100) used to form a polymeric film(110) with microcapillaries (103). The extruder (100) includes amaterial housing (105), a material hopper (107), a screw (109), a dieassembly (111) and electronics (115). The extruder (100) is shownpartially in cross-section to reveal the screw (109) within the materialhousing (105). While a screw-type extruder is depicted, a variety ofextruders (e.g., single screw, twin screw, etc.) may be used to performthe extrusion of the material through the extruder (100) and dieassembly (111). One or more extruders may be used with one or more dieassemblies. Electronics (115) may include, for example, controllers,processors, motors and other equipment used to operate the extruder.

Raw materials (e.g. thermoplastic materials) (117) are placed into thematerial hopper (107) and passed into the housing (105) for blending.The raw materials (117) are heated and blended by rotation of the screw(109) rotationally positioned in the housing (105) of the extruder(100). A motor (121) may be provided to drive the screw (109) or otherdriver to advance the raw materials (117). Heat and pressure are appliedas schematically depicted from a heat source T and a pressure source P(e.g., the screw (109)), respectively, to the blended material to forcethe raw material (117) through the die assembly (111) as indicated bythe arrow. The raw materials (117) are melted and conveyed through theextruder (100) and die assembly (111). The molten raw material (117)passes through the die assembly (111) and is formed into the desiredshape and cross section (referred to herein as the ‘profile’). The dieassembly (111) may be configured to extrude the molten raw material(117) into thin sheets of the polymeric film (110) as is describedfurther herein.

Microcapillary Film

FIGS. 2A-2F depict various views of a multi-layer film (210) which maybe produced, for example, by the extruder (100) and die assembly (111)of FIG. 1. As shown in FIGS. 2A-2F, the multi-layer film (210) is amicrocapillary film. The multi-layer film (210) is depicted as beingmade up of multiple layers (250 a,b) of thermoplastic material. The film(210) also has channels (220) positioned between the layers (250 a,b).

The multi-layer film (210) may also have an elongate profile as shown inFIG. 2C. This profile is depicted as having a wider width W relative toits thickness T. The thickness T may be in the range of from 100 to2,000 μm (e.g., from 250 to 2000 μm). The channels (220) may have adimension φ (e.g., a width or diameter) in the range of from 50 to 500μm (e.g., from 100 to 500 μm, or 250 to 500 μm), and have a spacing Sbetween the channels (220) in the range of from 50 to 500 μm (e.g., from100 to 500 μm, or 250 to 500 μm). Additionally, the selected dimensionsmay be proportionally defined. For example, the channel dimension φ maybe a diameter of about 30% of thickness T.

As shown, layers (250 a,b) are made of a matrix thermoplastic materialand channels (220) have a channel fluid (212) therein. The channel fluidmay comprise, for example, various materials, such as air, gas,polymers, etc., as will be described further herein. Each layer (250a,b) of the multi-layer film (210) may be made of various polymers, suchas those described further herein. Each layer may be made of the samematerial or of a different material. While only two layers (250 a,b) aredepicted, the multi-layer film (210) may have any number of layers.

It should be noted that when the same thermoplastic material is employedfor the layers (250 a,b), then a single layer (250) can result in thefinal product, due to fusion of the two streams of the matrix layerscomprised of the same polymer in a molten state merging shortly beforeexiting the die. This phenomenon is depicted in FIG. 2G.

Channels (220) may be positioned between one or more sets of layers (250a,b) to define microcapillaries (252) therein. The channel fluid (212)may be provided in the channels (220). Various numbers of channels (220)may be provided as desired. The multiple layers may also have the sameor different profiles (or cross-sections). The characteristics, such asshape of the layers (250 a,b) and/or channels (220) of the film (210),may be defined by the configuration of the die assembly used to extrudethe matrix material as will be described more fully herein.

The microcapillary film (210) has a first end (214) and a second end(216). One or more channels (220) are disposed in parallel in the matrix(218) from the first end (214) to the second end (216). The one or morechannels (220) can have a diameter of at least 250 μm, or in the rangeof from 250 to 1990 μm, from 250 to 990 μm, from 250 to 890 μm, from 250to 790 μm, from 250 to 690 μm, or from 250 to 590 μm. The one or morechannels (220) may have a cross sectional shape selected from the groupconsisting of circular, rectangular, oval, star, diamond, triangular,square, hexagonal, pentagonal, octagonal, the like, and combinationsthereof.

The matrix (218) comprises one or more matrix thermoplastic materials.Such matrix thermoplastic materials include, but are not limited to,polyolefins (e.g., polyethylenes, polypropylenes, etc.); polyamides(e.g., nylon 6); polyvinylidene chloride; polyvinylidene fluoride;polycarbonate; polystyrene; polyethylene terephthalate; polyurethane;and polyester. Specific examples of matrix thermoplastic materialsinclude those listed on pages 5 through 11 of PCT Published ApplicationNo. WO 2012/094315, titled “Microcapillary Films and Foams ContainingFunctional Filler Materials,” which are herein incorporated byreference.

The one or more channel fluids (212) may include a variety of fluids,such as air, other gases, or channel thermoplastic material. Channelthermoplastic materials include, but are not limited to, polyolefins(e.g., polyethylenes, polypropylenes, etc.); polyamides (e.g., nylon 6);polyvinylidene chloride; polyvinylidene fluoride; polycarbonate;polystyrene; polyethylene terephthalate; polyurethane; and polyester. Aswith the matrix (218) materials discussed above, specific examples ofthermoplastic materials suitable for use as channel fluids (212) includethose listed on pages 5 through 11 of PCT Published Application No. WO2012/094315.

Annular Microcapillary Product Extruder Assemblies

FIGS. 3A and 3B depict example extruder assemblies (300 a,b) used toform a multi-layer, annular microcapillary product (310 a,b) havingmicrocapillaries (303). The extruder assemblies (300 a,b) may be similarto the extruder (100) of FIG. 1, except that the extruder assemblies(300 a,b) include multiple extruders (100 a,b,c), with combined annularmicrocapillary co-extrusion die assemblies (311 a,b) operativelyconnected thereto. The annular die assemblies (311 a,b) have die inserts(353) configured to extrude annular microcapillary products, such asfilm (310) as shown in FIGS. 4A-4C, tubing (310 a) as shown in FIGS. 5,6A, and 6B, and/or molded shapes (310 b), as shown in FIG. 3B.

FIG. 3A depicts a first configuration of an extruder assembly (300 a)with three extruders (100 a,b,c) operatively connected to the combinedannular microcapillary co-extrusion die assembly (311 a). In an example,two of the three extruders may be matrix extruders (100 a,b) used tosupply thermoplastic material (e.g., polymer) (117) to the die assembly(311 a) to form layers of the annular microcapillary product (310 a). Athird of the extruders may be a microcapillary (or core layer) extruder(100 c) to provide a microcapillary material, such as a thermoplasticmaterial (e.g., polymer melt) (117), into the microcapillaries (303) toform a microcapillary phase (or core layer) therein.

The die insert (353) is provided in the die assembly (311 a) to combinethe thermoplastic material (117) from the extruders (100 a,b,c) into theannular microcapillary product (310 a). As shown in FIG. 3A, the annularmicrocapillary product may be a blown tubing (310 a) extruded upwardlythrough the die insert (353) and out the die assembly (311 a). Annularfluid (312 a) from a fluid source (319 a) may be passed through theannular microcapillary product (310 a) to shape the annularmicrocapillary tubing (310 a) during extrusion as shown in FIG. 3A, orbe provided with a molder (354) configured to produce an annularmicrocapillary product in the form of an annular microcapillary molding(or molded product), such as a bottle (310 b), shown in FIG. 3B.

FIG. 3B shows a second configuration of an extruder assembly (300 b).The extruder assembly (300 b) is similar to the extruder assembly (300a), except that the microcapillary extruder (100 c) has been replacedwith a microcapillary fluid source (319 b). The extruders (100 a,b)extrude thermoplastic material (as in the example of FIG. 3A) and themicrocapillary fluid source (319 b) may emit microcapillary material inthe form of a microcapillary fluid (312 b) through the die insert (353)of the die assembly (311 b). The two matrix extruders (100 a,b) emitthermoplastic layers, with the microcapillary fluid source (319 b)emitting microcapillary fluid (312 b) into the microcapillaries (303)therebetween to form the annular microcapillary product (310 b). In thisversion, the annular die assembly (311 b) may form film or blownproducts as in FIG. 3A, or be provided with a molder (354) configured toproduce an annular microcapillary product in the form of an annularmicrocapillary molding, such as a bottle, (310 b).

While FIGS. 3A and 3B show each extruder (100 a,b,c) as having aseparate material housing (105), material hopper (107), screw (109),electronics (115), motor (121), part or all of the extruders (100) maybe combined. For example, the extruders (100 a,b,c) may each have theirown hopper (107), and share certain components, such as electronics(115) and die assembly (311 a,b). In some cases, the fluid sources (319a,b) may be the same fluid source providing the same fluid (312 a,b),such as air.

The die assemblies (311 a,b) may be operatively connected to theextruders (100 a,b,c) in a desired orientation, such as a verticalupright position as shown in FIG. 3A, a vertical downward position asshown in FIG. 3B, or a horizontal position as shown in FIG. 1. One ormore extruders may be used to provide the polymeric matrix material thatforms the layers and one or more material sources, such as extruder (100c) and/or microcapillary fluid source (319 b), may be used to providethe microcapillary material. Additionally, as described in more detailbelow, the die assemblies may be configured in a crosshead position forco-extrusion with a conductive core.

Annular Microcapillary Products

FIGS. 4A-4C depict various views of an annular microcapillary productwhich may be in the form of a film (310, 310′) produced, for example, bythe extruders (300 a,b) and die assemblies (311 a,b) of FIGS. 3A and/or3B. As shown in FIGS. 4A and 4B, the annular microcapillary product(310) may be similar to the film (210), except that the annularmicrocapillary product (310) is formed from the annular die assemblies(311 a,b) into polymeric matrix layers (450 a,b) with microcapillaries(303, 303′) therein. The polymeric matrix layers (450 a,b) collectivelyform a polymeric matrix (418) of the annular microcapillary product(310). The layers (450 a,b) have parallel, linear channels (320)defining microcapillaries (303) therein.

As shown in FIGS. 4B and 4C, the annular microcapillary product (310,310′) may be extruded with various microcapillary material (117) ormicrocapillary fluid (312 b) therein. The microcapillaries may be formedin channels (320, 320′) with various cross-sectional shapes. In theexample of FIG. 4B, the channels (320) have an arcuate cross-sectiondefining the microcapillaries (303) with the microcapillary material(117) therein. The microcapillary material (117) is in the channels(320) between the matrix layers (450 a,b) that form the polymeric matrix(418). The microcapillary material (117) forms a core layer between thepolymeric matrix layers (450 a,b).

In the example of FIG. 4C, the channels (320′) have an ellipticalcross-section defining microcapillaries (303′) with the microcapillarymaterial (312 b) therein. The microcapillary material (312 b) isdepicted as fluid (e.g., air) in the channels (320′) between the layers(450 a,b) that form the polymeric matrix (418).

It should be noted that, as with the films described above, the annularmicrocapillary product can take the form of a single-layer product whenthe same matrix material is employed for the layers (450 a,b). This isdue to the fusion of the two streams of the matrix layers in a moltenstate merging shortly before exiting the die.

The materials used to form the annular microcapillary products asdescribed herein may be selected for a given application. For example,the material may be a plastic, such as a thermoplastic or thermosetmaterial. When a thermoplastic material is employed, the thermoplasticmaterial (117) forming the polymeric matrix (418) and/or themicrocapillary material (117) may be selected from those materialsuseful in forming the film (210) as described above. Accordingly, theannular microcapillary products may be made of various materials, suchas polyolefins (e.g., polyethylene or polypropylene). For example, inFIGS. 4A and 4B, the polymeric matrix (418) may be a low-densitypolyethylene and the microcapillary material (117) may be polypropylene.As another example, in FIG. 4C the polymeric matrix (418) can be made oflow-density polyethylene with air as the microcapillary material (312b).

Referring to FIG. 5, the fluid source (319 a) may pass annular fluid(e.g., air) (312 a) through the annular microcapillary product (310 a)to support the tubular shape during extrusion. The die assembly (311 a)may form the multi-layer, annular microcapillary product (310 a,310 a′)into a tubular shape as shown in FIGS. 6A-6B.

As also shown by FIGS. 6A and 6B, the thermoplastic materials formingportions of the multi-layer, annular microcapillary product (310 a,310a′) may be varied. In the example shown in FIGS. 4A, 4B, and 6A, thelayers (450 a,b) forming polymeric matrix (418) may have a differentmaterial from the microcapillary material (117) in the microcapillaries(303) as schematically indicated by the black channels (320) and whitepolymeric matrix (418). In another example, as shown in FIG. 6B, thelayers (450 a,b) forming a polymeric matrix (418) and the material inmicrocapillaries (303) may be made of the same material, such aslow-density polyethylene, such that the polymeric matrix (418) and thechannels (320) are both depicted as black.

Die Assemblies for Annular Microcapillary Products

FIGS. 7A-9D depict example configurations of die assemblies(711,811,911) usable as the die assembly (311). While FIGS. 7A-9D showexamples of possible die assembly configurations, combinations and/orvariations of the various examples may be used to provide the desiredmulti-layer, annular microcapillary product, such as those shown in theexamples of FIGS. 4A-6B.

FIGS. 7A-7D depict partial cross-sectional, longitudinalcross-sectional, end, and detailed cross-sectional views, respectively,of the die assembly (711). FIGS. 8A-8D depict partial cross-sectional,longitudinal cross-sectional, end, and detailed cross-sectional views,respectively, of the die assembly (811). FIGS. 9A-9D depict partialcross-sectional, longitudinal cross-sectional, end, and detailedcross-sectional views, respectively, of the die assembly (911). The dieassemblies (711, 811) may be used, for example, with the extruderassembly (300 a) of FIG. 3A and the die assembly (911) may be used, forexample, with the extruder assembly (300 b) of FIG. 3B to form annularmicrocapillary products, such as those described herein.

As shown in FIGS. 7A-7D, the die assembly (711) includes a shell (758),an inner manifold (760), an outer manifold (762), a cone (764), and adie insert (768). The shell (758) is a tubular member shaped to receivethe outer manifold (762). The outer manifold (762), die insert (768),and the inner manifold (760) are each flange shaped members stacked andconcentrically received within the shell (758). While an inner manifold(760) and an outer manifold (762) are depicted, one or more inner and/orouter manifolds or other devices capable of providing flow channels forforming layers of the polymeric matrix may be provided.

The die insert (768) is positioned between the outer manifold (762) andthe inner manifold (760). The inner manifold (760) has the cone (764) atan end thereof extending through the die insert (768) and the outermanifold (762) and into the shell (758). The die assembly (711) may beprovided with connectors, such as bolts (not shown), to connect portionsof the die assembly (711).

Referring now to FIG. 7B, annular matrix channels (774 a,b) are definedbetween the shell (758) and the outer manifold (762) and between the dieinsert (768) and the inner manifold (760), respectively. Thethermoplastic material (117) is depicted passing through the matrixchannels (774 a,b) as indicated by the arrows to form the layers (450a,b) of the multi-layer, annular microcapillary product (710). Theannular microcapillary product (710) may be any of the annularmicrocapillary products described herein, such as (310 a,b).

A microcapillary channel (776) is also defined between the die insert(768) and the outer manifold (762). The microcapillary channel (776) maybe coupled to the microcapillary material source for passing themicrocapillary material (117,312 b) through the die assembly (711) andbetween the layers (450 a,b) to form the microcapillaries (303) therein.The fluid channel (778) extends through the inner manifold (760) and thecone (764). Annular fluid (312 a) from fluid source (319 a) flowsthrough the fluid channel (778) and into the product (710 a).

The die insert (768) may be positioned concentrically between the innermanifold (760) and the outer manifold (762) to provide uniformdistribution of polymer melt flow through the die assembly (711). Thedie insert (762) may be provided with a distribution channel (781) alongan outer surface thereof to facilitate the flow of the microcapillarymaterial (117/312 b) therethrough.

The matrix channels (774 a,b) and the microcapillary channel (776)converge at convergence (779) and pass through an extrusion outlet (780)such that thermoplastic material flowing through matrix channels (774a,b) forms layers (450 a,b) with microcapillary material (117/312 b)from microcapillary channel (776) therebetween. The outer manifold (762)and die insert (768) each terminate at an outer nose (777 a) and aninsert nose (777 b), respectively. As shown in FIG. 7D, the outer nose(777 a) extends a distance A further toward the extrusion outlet (780)and/or a distance A further away from the extrusion outlet (780) thanthe nose (777 b).

The die assemblies (811, 911) of FIGS. 8A-9D may be similar to the dieassembly (711) of FIGS. 7A-7D, except that a position of noses (777 a,b,977 a,b) of the die insert (768, 968) relative to the outer manifold(762) may be varied. The position of the noses may be adjusted to definea flow pattern, such as asymmetric or symmetric therethrough. As shownin FIGS. 7A-7D, the die assembly (711) is in an asymmetric flowconfiguration with nose (777 b) of the die insert (768) positioned adistance A from the nose (777 a) of the outer manifold (762). As shownin FIGS. 8A-8D, the die assembly (811) is in the symmetric flowconfiguration with the noses (777 a,b) of the die insert (768) and theouter manifold (762) being flush.

FIGS. 9A-9D and 10 depict an annular die insert (968) provided withfeatures to facilitate the creation of the channels (320),microcapillaries (303), and/or insertion of the microcapillary material(117/312 b) therein (see, e.g., FIGS. 4A-4B). The die insert (968)includes a base (982), a tubular manifold (984), and a tip (986). Thebase (982) is a ring shaped member that forms a flange extending from asupport end of the annular microcapillary manifold (984). The base (982)is supportable between the inner manifold (760) and outer manifold(762). The outer manifold (762) has an extended nose (977 a) and the dieinsert (968) has an extended nose (977 b) positioned flush to each otherto define a symmetric flow configuration through the die assembly (911).

The tip (986) is an annular member at a flow end of the tubular manifold(984). An inner surface of the tip (986) is inclined and shaped toreceive an end of the cone (764). The tip (986) has a larger outerdiameter than the annular microcapillary manifold (984) with an inclinedshoulder (990) defined therebetween. An outer surface of the tip (986)has a plurality of linear, parallel microcapillary flow channels (992)therein for the passage of the microcapillary material (117/312 b)therethrough. The outer manifold 762 terminates in a sharp edge (983 a)along nose (977 a) and tip (986) terminates in a sharp edge (983 b)along nose (977 b).

The annular microcapillary manifold (984) is an annular member extendingbetween the base (982) and the tip (986). The annular microcapillarymanifold (984) is supportable between a tubular portion of the innermanifold (760) and the outer manifold (762). The annular microcapillarymanifold (984) has a passage (988) to receive the inner manifold (760).

The distribution channel (781) may have a variety of configurations. Asshown in FIGS. 9A-9D, an outer surface of the annular microcapillarymanifold (984) has the distribution channel (781) therealong for thepassage of material therethrough. The distribution channel (781) may bein fluid communication with the microcapillary material (117/312 b) viathe microcapillary channel (776) as schematically depicted in FIG. 9B.The distribution channel (781) may be positioned about the die insert(968) to direct the microcapillary material around a circumference ofthe die insert (968). The die insert (968) and/or distribution channel(781) may be configured to facilitate a desired amount of flow ofmicrocapillary material (117/312 b) through the die assembly. Thedistribution channel (781) defines a material flow path for the passageof the microcapillary material between the die insert (968) and theouter manifold (762).

A small gap may be formed between the die insert (968) and the outermanifold (762) that allows the microcapillary material (117/312 b) toleak out of the distribution channel (781) to distribute themicrocapillary material (117/312 b) uniformly through the die assembly(911). The distribution channel (781) may be in the form of a cavity orchannel extending a desired depth into the die insert (968) and/or theouter manifold (760). For example, as shown in FIGS. 7A-9D, thedistribution channel (781) may be a space defined between the outersurface of the die insert (968) and the outer manifold (760). As shownin FIG. 10, the distribution channel (781, 1081) is a helical grooveextending a distance along the outer surface of the tubular manifold(984). Part or all of the distribution channel (781, 1081) may belinear, curved, spiral, cross-head, and/or combinations thereof.

Coated Conductor

The above-described annular microcapillary products can be used toprepare coated conductors, such as a cable. “Cable” and “power cable”mean at least one conductor within a sheath, e.g., an insulationcovering and/or a protective outer jacket. “Conductor” denotes one ormore wire(s) or fiber(s) for conducting heat, light, and/or electricity.The conductor may be a single-wire/fiber or a multi-wire/fiber and maybe in strand form or in tubular form. Non-limiting examples of suitableconductors include metals such as silver, gold, copper, carbon, andaluminum. The conductor may also be optical fiber made from either glassor plastic. “Wire” means a single strand of conductive metal, e.g.,copper or aluminum, or a single strand of optical fiber. Typically, acable is two or more wires or optical fibers bound together, often in acommon insulation covering and/or protective jacket. The individualwires or fibers inside the sheath may be bare, covered or insulated.Combination cables may contain both electrical wires and optical fibers.When the cable is a power cable, the cable can be designed for low,medium, and/or high voltage applications. Typical cable designs areillustrated in U.S. Pat. Nos. 5,246,783, 6,496,629 and 6,714,707. Whenthe cable is a telecommunication cable, the cable can be designed fortelephone, local area network (LAN)/data, coaxial CATV, coaxial RF cableor a fiber optic cable.

The above-described annular microcapillary products can constitute atleast one polymeric coating layer in a cable, which is elongated in thesame direction of elongation as the conductor or conductive core of thecable. As such, the polymeric coating can surround at least a portion ofthe conductor. In surrounding the conductor, the polymeric coating canbe either in direct contact with the conductor or can be in indirectcontact with the conductor by being placed on one or more intercedinglayers between the conductor and the polymeric coating. The polymericcoating comprises a polymeric matrix material and a plurality ofmicrocapillaries which extend substantially in the direction ofelongation of the polymeric coating. In various embodiments, themicrocapillaries can be radially placed around the polymeric coating.Additionally, the microcapillaries can be spaced apart equidistantly orsubstantially equidistantly relative to one another.

One or more of the above-described die assemblies for producing annularmicrocapillary products can be modified to permit a conductor to passtherethrough, thereby allowing the polymeric coating comprising apolymeric matrix material and a plurality of microcapillaries to becoextruded onto the conductor or an interceding layer. Such aconfiguration is commonly known in the art as a crosshead die (see,e.g., US 2008/0193755 A1, US 2014/0072728 A1, and US 2013/0264092 A1).Specifically, the inner manifold (760) and cone (764) in FIGS. 7A, 8Aand 9A can be modified to create a wire- or conductor-passing hole. Asone of ordinary skill in the art would recognize, all the parts close tothe die exit can be modified such that the extrusion materials are ableto coat onto a conductor (or interceding layer) traveling through thewire- or conductor-passing hole. An additional part with molding passagecan be fabricated. Such modifications are within the capabilities of onehaving ordinary skill in the art.

In an exemplary microcapillary extrusion coating process, a conductorcore through an extrusion coating equipment can be pulled by a retractorto continuously move through the wire-passing hole of the inner manifold(760) to go through the projection end and then pass through the moldingpassage of the outer die. While the conductor core is moving, thepolymer melt is injected by pressure into the material-supplyingpassages, flows toward to the wiring coating passage, and then into themolding passage at the outlet to coat onto the outer surface of theconductor core which is passing through the molding passage.Subsequently, the coated conductor core continues to move through themolding passage to outside the die, and then it can be cooled andhardened.

In preparing the polymeric coating, any of the above-described polymerscan be used as the polymeric matrix material. In various embodiments,the polymer employed as the polymeric matrix material can comprise anethylene-based polymer. As used herein, “ethylene-based” polymers arepolymers prepared from ethylene monomers as the primary (i.e., greaterthan 50 weight percent (“wt %”)) monomer component, though otherco-monomers may also be employed. “Polymer” means a macromolecularcompound prepared by reacting (i.e., polymerizing) monomers of the sameor different type, and includes homopolymers and interpolymers.“Interpolymer” means a polymer prepared by the polymerization of atleast two different monomer types. This generic term includes copolymers(usually employed to refer to polymers prepared from two differentmonomer types), and polymers prepared from more than two differentmonomer types (e.g., terpolymers (three different monomer types) andtetrapolymers (four different monomer types)).

In various embodiments, the ethylene-based polymer can be an ethylenehomopolymer. As used herein, “homopolymer” denotes a polymer comprisingrepeating units derived from a single monomer type, but does not excluderesidual amounts of other components used in preparing the homopolymer,such as chain transfer agents.

In an embodiment, the ethylene-based polymer can be anethylene/alpha-olefin (“α olefin”) interpolymer having an α-olefincontent of at least 1 wt %, at least 5 wt %, at least 10 wt %, at least15 wt %, at least 20 wt %, or at least 25 wt % based on the entireinterpolymer weight. These interpolymers can have an α-olefin content ofless than 50 wt %, less than 45 wt %, less than 40 wt %, or less than 35wt % based on the entire interpolymer weight. When an α-olefin isemployed, the α-olefin can be a C₃₋₂₀ (i.e., having 3 to 20 carbonatoms) linear, branched or cyclic α-olefin. Examples of C₃₋₂₀ α-olefinsinclude propene, 1 butene, 4-methyl-1-pentene, 1-hexene, 1-octene,1-decene, 1 dodecene, 1 tetradecene, 1 hexadecene, and 1-octadecene. Theα-olefins can also have a cyclic structure such as cyclohexane orcyclopentane, resulting in an α-olefin such as 3 cyclohexyl-1-propene(allyl cyclohexane) and vinyl cyclohexane. Illustrativeethylene/α-olefin interpolymers include ethylene/propylene,ethylene/1-butene, ethylene/1 hexene, ethylene/1 octene,ethylene/propylene/1-octene, ethylene/propylene/1-butene, andethylene/1-butene/1 octene.

Ethylene-based polymers also include interpolymers of ethylene with oneor more unsaturated acid or ester monomers, such as unsaturatedcarboxylic acids or alkyl (alkyl)acrylates. Such monomers include, butare not limited to, vinyl acetate, methyl acrylate, methyl methacrylate,ethyl acrylate, ethyl methacrylate, butyl acrylate, acrylic acid, andthe like. Accordingly, ethylene-based polymers can include interpolymerssuch as poly(ethylene-co-methyl acrylate) (“EMA”),poly(ethylene-co-ethyl acrylate) (“EEA”), poly(ethylene-co-butylacrylate) (“EBA”), and poly(ethylene-co-vinyl acetate) (“EVA”).

In various embodiments, the ethylene-based polymer can be used alone orin combination with one or more other types of ethylene-based polymers(e.g., a blend of two or more ethylene-based polymers that differ fromone another by monomer composition and content, catalytic method ofpreparation, etc). If a blend of ethylene-based polymers is employed,the polymers can be blended by any in-reactor or post-reactor process.

In an embodiment, the ethylene-based polymer can be a low-densitypolyethylene (“LDPE”). LDPEs are generally highly branched ethylenehomopolymers, and can be prepared via high pressure processes (i.e.,HP-LDPE). LDPEs suitable for use herein can have a density ranging from0.91 to 0.94 g/cm³. In various embodiments, the ethylene-based polymeris a high-pressure LDPE having a density of at least 0.915 g/cm³, butless than 0.94 g/cm³, or in the range of from 0.924 to 0.938 g/cm³.Polymer densities provided herein are determined according to ASTMInternational (“ASTM”) method D792. LDPEs suitable for use herein canhave a melt index (I₂) of less than 20 g/10 min., or ranging from 0.1 to10 g/10 min., from 0.5 to 5 g/10 min., from 1 to 3 g/10 min., or an I₂of 2 g/10 min. Melt indices provided herein are determined according toASTM method D1238. Unless otherwise noted, melt indices are determinedat 190° C. and 2.16 Kg (i.e., I₂). Generally, LDPEs have a broadmolecular weight distribution (“MWD”) resulting in a relatively highpolydispersity index (“PDI;” ratio of weight-average molecular weight tonumber-average molecular weight).

In an embodiment, the ethylene-based polymer can be a linear-low-densitypolyethylene (“LLDPE”). LLDPEs are generally ethylene-based polymershaving a heterogeneous distribution of comonomer (e.g., α-olefinmonomer), and are characterized by short-chain branching. For example,LLDPEs can be copolymers of ethylene and α-olefin monomers, such asthose described above. LLDPEs suitable for use herein can have a densityranging from 0.916 to 0.925 g/cm³. LLDPEs suitable for use herein canhave a melt index (I₂) ranging from 1 to 20 g/10 min., or from 3 to 8g/10 min.

In an embodiment, the ethylene-based polymer can be a very-low-densitypolyethylene (“VLDPE”). VLDPEs may also be known in the art asultra-low-density polyethylenes, or ULDPEs. VLDPEs are generallyethylene-based polymers having a heterogeneous distribution of comonomer(e.g., α-olefin monomer), and are characterized by short-chainbranching. For example, VLDPEs can be copolymers of ethylene andα-olefin monomers, such as one or more of those α-olefin monomersdescribed above. VLDPEs suitable for use herein can have a densityranging from 0.87 to 0.915 g/cm³. VLDPEs suitable for use herein canhave a melt index (I₂) ranging from 0.1 to 20 g/10 min., or from 0.3 to5 g/10 min.

In an embodiment, the ethylene-based polymer can be a medium-densitypolyethylene (“MDPE”). MDPEs are ethylene-based polymers havingdensities generally ranging from 0.926 to 0.950 g/cm³. In variousembodiments, the MDPE can have a density ranging from 0.930 to 0.949g/cm³, from 0.940 to 0.949 g/cm³, or from 0.943 to 0.946 g/cm³. The MDPEcan have a melt index (I₂) ranging from 0.1 g/10 min, or 0.2 g/10 min,or 0.3 g/10 min, or 0.4 g/10 min, up to 5.0 g/10 min, or 4.0 g/10 min,or, 3.0 g/10 min or 2.0 g/10 min, or 1.0 g/10 min.

In an embodiment, the ethylene-based polymer can be a high-densitypolyethylene (“HDPE”). HDPEs are ethylene-based polymers generallyhaving densities greater than 0.940 g/cm³. In an embodiment, the HDPEhas a density from 0.945 to 0.97 g/cm³, as determined according to ASTMD 792. The HDPE can have a peak melting temperature of at least 130° C.,or from 132 to 134° C. The HDPE can have a melt index (I₂) ranging from0.1 g/10 min, or 0.2 g/10 min, or 0.3 g/10 min, or 0.4 g/10 min, up to5.0 g/10 min, or 4.0 g/10 min, or, 3.0 g/10 min or 2.0 g/10 min, or 1.0g/10 min, or 0.5 g/10 min. Also, the HDPE can have a PDI in the range offrom 1.0 to 30.0, or in the range of from 2.0 to 15.0, as determined bygel permeation chromatography.

In an embodiment, the ethylene-based polymer can comprise a combinationof any two or more of the above-described ethylene-based polymers.

In an embodiment, the polymeric matrix material can comprise LDPE. In anembodiment, the polymeric matrix material is LDPE.

In an embodiment, the polymeric matrix material can comprise MDPE. In anembodiment, the polymeric matrix material is MDPE.

Production processes used for preparing ethylene-based polymers arewide, varied, and known in the art. Any conventional or hereafterdiscovered production process for producing ethylene-based polymershaving the properties described above may be employed for preparing theethylene-based polymers described herein. In general, polymerization canbe accomplished at conditions known in the art for Ziegler-Natta orKaminsky-Sinn type polymerization reactions, that is, at temperaturesfrom 0 to 250° C., or 30 or 200° C., and pressures from atmospheric to10,000 atmospheres (1,013 megaPascal (“MPa”)). In most polymerizationreactions, the molar ratio of catalyst to polymerizable compoundsemployed is from 10-12:1 to 10 1:1, or from 10-9:1 to 10-5:1.

Examples of suitable commercially available ethylene-based polymersinclude, but are not limited to AXELERON™ GP C-0588 BK (LDPE), AXELERON™FO 6548 BK (MDPE), AXELERON™ GP A-7530 NT (LLDPE), AXELERON™ GP G-6059BK (LLDPE), AXELERON™ GP K-3479 BK (HDPE), AXELERON™ GP A-1310 NT(HDPE), and AXELERON™ FO B-6549 NT (MDPE), all of which are commerciallyavailable from The Dow Chemical Company, Midland, Mich., USA.

Polypropylene-based polymers, such as homopolymer, random copolymer,heterophasic copolymer, and high-crystalline homopolymer polypropylenesare commercially available from Braskem Corp.

In preparing the polymeric coating, any of the above-described materialscan also be used as the microcapillary material.

In various embodiments, the microcapillary material is a gas. In one ormore embodiments, the microcapillary material is air. In suchembodiments, the microcapillaries define individual, discrete voidspaces which are completely surrounded by the polymeric matrix materialwhen viewed as a cross-section taken orthogonal to the direction ofelongation of the microcapillaries.

In one or more embodiments, the microcapillary material can be anelastomeric microcapillary material. As known in the art, elastomers arematerials which experience large reversible deformations underrelatively low stress. In any embodiments where the microcapillaries arefilled with a polymeric microcapillary material, the microcapillariescan define individual, discrete polymer-filled segments which arecompletely surrounded by the polymeric matrix material when viewed as across-section taken orthogonal to the direction of elongation of themicrocapillaries.

In various embodiments, the elastomer can be an olefin elastomer. Olefinelastomers include both polyolefin homopolymers and interpolymers.Examples of the polyolefin interpolymers are ethylene/α-olefininterpolymers and propylene/α-olefin interpolymers. In such embodiments,the α-olefin can be any of those described above with respect to theethylene-based polymer. Illustrative polyolefin copolymers includeethylene/propylene, ethylene/butene, ethylene/1-hexene,ethylene/1-octene, ethylene/styrene, and the like. Illustrativeterpolymers include ethylene/propylene/1-octene,ethylene/propylene/butene, ethylene/butene/1-octene, andethylene/butene/styrene. The copolymers can be random or blocky.

Olefin elastomers can also comprise one or more functional groups suchas an unsaturated ester or acid or silane, and these elastomers(polyolefins) are well known and can be prepared by conventionalhigh-pressure techniques. The unsaturated esters can be alkyl acrylates,alkyl methacrylates, or vinyl carboxylates. The alkyl groups can have 1to 8 carbon atoms and preferably have 1 to 4 carbon atoms. Thecarboxylate groups can have 2 to 8 carbon atoms and preferably have 2 to5 carbon atoms. The portion of the copolymer attributed to the estercomonomer can be in the range of 1 up to 50 percent by weight based onthe weight of the copolymer. Examples of the acrylates and methacrylatesare ethyl acrylate, methyl acrylate, methyl methacrylate, t-butylacrylate, n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexylacrylate. Examples of the vinyl carboxylates are vinyl acetate, vinylpropionate, and vinyl butanoate. Examples of the unsaturated acidsinclude acrylic acids or maleic acids. One example of an unsaturatedsilane is vinyl trialkoxysilane (e.g., vinyl trimethoxysilane and vinyltriethoxysilane).

More specific examples of the olefin elastomers useful in this inventioninclude very-low-density polyethylene (“VLDPE”) (e.g., FLEXOMER™ethylene/1-hexene polyethylene made by The Dow Chemical Company),homogeneously branched, linear ethylene/α-olefin copolymers (e.g.TAFMER™ by Mitsui Petrochemicals Company Limited and EXACT™ by ExxonChemical Company), and homogeneously branched, substantially linearethylene/α-olefin polymers (e.g., AFFINITY™ and ENGAGE™ polyethyleneavailable from The Dow Chemical Company).

The olefin elastomers useful herein also include propylene, butene, andother alkene-based copolymers, e.g., copolymers comprising a majority ofunits derived from propylene and a minority of units derived fromanother α-olefin (including ethylene). Exemplary propylene polymersuseful herein include VERSIFY™ polymers available from The Dow ChemicalCompany, and VISTAMAXX™ polymers available from ExxonMobil ChemicalCompany.

Olefin elastomers can also include ethylene-propylene-diene monomer(“EPDM”) elastomers and chlorinated polyethylenes (“CPE”). Commercialexamples of suitable EPDMs include NORDEL™ EPDMs, available from The DowChemical Company. Commercial examples of suitable CPEs include TYRIN™CPEs, available from The Dow Chemical Company.

Olefin elastomers, particularly ethylene elastomers, can have a densityof less than 0.91 g/cm³ or less than 0.90 g/cm³. Ethylene copolymerstypically have a density greater than 0.85 g/cm³ or greater than 0.86,g/cm³. Olefin elastomers can have a melt index (I₂) greater than 0.10g/10 min., or greater than 1 g/10 min. Olefin elastomers can have a meltindex of less than 500 g/10 min. or less than 100 g/10 min.

Other suitable olefin elastomers include olefin block copolymers (suchas those commercially available under the trade name INFUSE™ from TheDow Chemical Company, Midland, Mich., USA), mesophase-separated olefinmulti-block interpolymers (such as described in U.S. Pat. No.7,947,793), and olefin block composites (such as described in U.S.Patent Application Publication No. 2008/0269412, published on Oct. 30,2008).

In various embodiments, the elastomer useful as the microcapillarymaterial can be a non-olefin elastomer. Non-olefin elastomers usefulherein include silicone and urethane elastomers, styrene-butadienerubber (“SBR”), nitrile rubber, chloroprene, fluoroelastomers,perfluoroelastomers, polyether block amides and chlorosulfonatedpolyethylene. Silicone elastomers are polyorganosiloxanes typicallyhaving an average unit formula R_(a)SiO_((4-a)/2) which may have alinear or partially-branched structure, but is preferably linear. Each Rmay be the same or different. R is a substituted or non-substitutedmonovalent hydrocarbyl group which may be, for example, an alkyl group,such as methyl, ethyl, propyl, butyl, and octyl groups; aryl groups suchas phenyl and tolyl groups; aralkyl groups; alkenyl groups, for example,vinyl, allyl, butenyl, hexenyl, and heptenyl groups; and halogenatedalkyl groups, for example chloropropyl and 3,3,3-trifluoropropyl groups.The polyorganosiloxane may be terminated by any of the above groups orwith hydroxyl groups. When R is an alkenyl group the alkenyl group ispreferably a vinyl group or hexenyl group. Indeed alkenyl groups may bepresent in the polyorganosiloxane on terminal groups and/or polymer sidechains.

Representative silicone rubbers or polyorganosiloxanes include, but arenot limited to, dimethylvinylsiloxy-terminated polydimethylsiloxane,trimethylsiloxy-terminated polydimethylsiloxane,trimethylsiloxy-terminated copolymer of methylvinylsiloxane anddimethylsiloxane, dimethylvinylsiloxy-terminated copolymer ofmethylvinylsiloxane and dimethylsiloxane,dimethylhydroxysiloxy-terminated polydimethylsiloxane,dimethylhydroxysiloxy-terminated copolymer of methylvinylsiloxane anddimethylsiloxane, methylvinylhydroxysiloxy-terminated copolymer ofmethylvinylsiloxane and dimethylsiloxane,dimethylhexenylsiloxy-terminated polydimethylsiloxane,trimethylsiloxy-terminated copolymer of methylhexenylsiloxane anddimethylsiloxane, dimethylhexenylsiloxy-terminated copolymer ofmethylhexenylsiloxane and dimethylsiloxane,dimethylvinylsiloxy-terminated copolymer of methylphenylsiloxane anddimethylsiloxane, dimethylhexenylsiloxy-terminated copolymer ofmethylphenylsiloxane and dimethylsiloxane,dimethylvinylsiloxy-terminated copolymer ofmethyl(3,3,3-trifluoropropyl)siloxane and dimethylsiloxane, anddimethylhexenylsiloxy-terminated copolymer ofmethyl(3,3,3-trifluoropropyl)siloxane and dimethylsiloxane.

Urethane elastomers are prepared from reactive polymers such aspolyethers and polyesters and isocyanate functional organic compounds.One typical example is the reaction product of a dihydroxy functionalpolyether and/or a trihydroxy functional polyether with toluenediisocyanate such that all of the hydroxy is reacted to form urethanelinkages leaving isocyanate groups for further reaction. This type ofreaction product is termed a prepolymer which may cure by itself onexposure to moisture or by the stoichiometric addition of polycarbinolsor other polyfunctional reactive materials which react with isocyanates.The urethane elastomers are commercially prepared having various ratiosof isocyanate compounds and polyethers or polyesters. The most commonurethane elastomers are those containing hydroxyl functional polyethersor polyesters and low molecular weight polyfunctional, polymericisocyanates. Another common material for use with hydroxyl functionalpolyethers and polyesters is toluene diisocyanate.

Nonlimiting examples of suitable urethane rubbers include thePELLETHANE™ thermoplastic polyurethane elastomers available from theLubrizol Corporation; ESTANE™ thermoplastic polyurethanes, TECOFLEX™thermoplastic polyurethanes, CARBOTHANE™ thermoplastic polyurethanes,TECOPHILIC™ thermoplastic polyurethanes, TECOPLAST™ thermoplasticpolyurethanes, and TECOTHANE™ thermoplastic polyurethanes, all availablefrom Noveon; ELASTOLLAN™ thermoplastic polyurethanes and otherthermoplastic polyurethanes available from BASF; and additionalthermoplastic polyurethane materials available from Bayer, Huntsman,Lubrizol Corporation, Merquinsa and other suppliers. Preferred urethanerubbers are those so-called “millable” urethanes such as MILLATHANE™grades from TSI Industries.

Additional information on such urethane materials can be found inGolding, Polymers and Resins, Van Nostrande, 1959, pages 325 et seq. andSaunders and Frisch, Polyurethanes, Chemistry and Technology, Part II,Interscience Publishers, 1964, among others.

Suitable commercially available elastomers for use as the microcapillarymaterial include, but are not limited to, ENGAGE™ polyolefin elastomersavailable from The Dow Chemical Company, Midland, Mich., USA. A specificexample of such an elastomer is ENGAGE™ 8200, which is anethylene/octene copolymer having a melt index (I₂) of 5.0 and a densityof 0.870 g/cm³.

In embodiments where an elastomer microcapillary material is employed,it may be desirable for the matrix material to have higher toughness,abrasion resistance, density, and/or flexural modulus relative to theelastomer. This combination affords a polymeric coating having a toughouter layer but with increased flexibility compared to a coating formedcompletely of the same matrix material. For example, in variousembodiments, the polymeric coating can have one or more of theabove-described elastomers as the microcapillary material with anethylene-based polymer, a polyamide (e.g., nylon 6), polybutyleneterephthalate (“PBT”), polyethylene terephthalate (“PET”), apolycarbonate, or combinations of two or more thereof as the polymericmatrix material. In various embodiments, the polymeric coating cancomprise an olefin elastomer as the microcapillary material and thepolymeric matrix material can be selected from the group consisting ofHDPE, MDPE, LLDPE, LDPE, a polyamide, PBT, PET, a polycarbonate, orcombinations of two or more thereof. In one or more embodiments, themicrocapillary material can comprise an ethylene/octene copolymer olefinelastomer and the polymeric matrix material can comprise MDPE.

The above-described polymeric matrix material, microcapillary material,or both can contain one or more additives, such as those typically usedin preparing cable coatings. For example, the polymeric matrix material,microcapillary material, or both can optionally contain a non-conductivecarbon black commonly used in cable jackets. In various embodiments, theamount of a carbon black in the composition can be greater than zero(>0), typically from 1, more typically from 2, and up to 3 wt %, basedon the total weight of the composition. In various embodiments, thecomposition can optionally include a conductive filler, such as aconductive carbon black, metal fibers, powders, or carbon nanotubes, ata high level for semiconductive applications.

Non-limiting examples of conventional carbon blacks include the gradesdescribed by ASTM N550, N472, N351, N110 and N660, Ketjen blacks,furnace blacks and acetylene blacks. Other non-limiting examples ofsuitable carbon blacks include those sold under the tradenames BLACKPEARLS®, CSX®, ELFTEX®, MOGUL®, MONARCH®, REGAL® and VULCAN®, availablefrom Cabot.

The polymeric matrix material, microcapillary material, or both canoptionally contain one or more additional additives, which are generallyadded in conventional amounts, either neat or as part of a masterbatch.Such additives include, but not limited to, flame retardants, processingaids, nucleating agents, foaming agents, crosslinking agents, fillers,pigments or colorants, coupling agents, antioxidants, ultravioletstabilizers (including UV absorbers), tackifiers, scorch inhibitors,antistatic agents, plasticizers, lubricants, viscosity control agents,anti-blocking agents, surfactants, extender oils, acid scavengers, metaldeactivators, vulcanizing agents, and the like.

In one or more embodiments, the polymeric matrix material, themicrocapillary material, or both can be crosslinkable. Any suitablemethods known in the art can be used to crosslink the matrix materialand/or the microcapillary material. Such methods include, but are notlimited to, peroxide crosslinking, silane functionalization for moisturecrosslinking, UV crosslinking, or e-beam cure. Such crosslinking methodsmay require the inclusion of certain additives (e.g., peroxides), asknown in the art.

In various embodiments, the polymeric matrix material, themicrocapillary material, or both can contain one or more adhesionmodifiers. Adhesion modifiers may be helpful in improving interfacialadhesion between the matrix material and the microcapillary material.Any known or hereafter discovered additive that improves adhesionbetween two polymeric materials may be used herein. Specific examples ofsuitable adhesion modifiers include, but are not limited to, maleicanhydride (“MAH”) grafted resins (e.g., MAH-grafted polyethylene,MAH-grafted ethylene vinyl acetate, MAH-grafted polypropylene), aminatedpolymers (e.g., amino-functionalized polyethylene), and the like, andcombinations of two or more thereof. MAH-grafted resins are commerciallyavailable under the AMPLIFY™ GR trade name from The Dow Chemical Company(Midland, Mich., USA) and under the FUSABOND™ trade name from DuPont(Wilmington, Del., USA).

Non-limiting examples of flame retardants include, but are not limitedto, aluminum hydroxide and magnesium hydroxide.

Non-limiting examples of processing aids include, but are not limitedto, fatty amides such as stearamide, oleamide, erucamide, or N,N′ethylene bis-stearamide; polyethylene wax; oxidized polyethylene wax;polymers of ethylene oxide; copolymers of ethylene oxide and propyleneoxide; vegetable waxes; petroleum waxes; non-ionic surfactants; siliconefluids; polysiloxanes; and fluoroelastomers such as Viton® availablefrom Dupon Performance Elastomers LLC, or Dynamar™ available from DyneonLLC.

A non-limiting example of a nucleating agent include Hyperform® HPN-20E(1,2 cyclohexanedicarboxylic acid calcium salt with zinc stearate) fromMilliken Chemicals, Spartanburg, S.C.

Non-limiting examples of fillers include, but are not limited to,various flame retardants, clays, precipitated silica and silicates,fumed silica, metal sulfides and sulfates such as molybdenum disulfideand barium sulfate, metal borates such as barium borate and zinc borate,metal anhydrides such as aluminum anhydride, ground minerals, andelastomeric polymers such as EPDM and EPR. If present, fillers aregenerally added in conventional amounts, e.g., from 5 wt % or less to 50or more wt % based on the weight of the composition.

In various embodiments, the polymeric coating on the coated conductorcan have a thickness ranging from 100 to 3,000 μm, from 500 to 3,000 μm,from 100 to 2,000 μm, from 100 to 1,000 μm, from 200 to 800 μm, from 200to 600 μm, from 300 to 1,000 μm, from 300 to 900 μm, or from 300 to 700μm. Additionally, the polymeric coating can have a thickness in therange of from 10 to 180 mils (254 μm to 4,572 μm).

Additionally, the average diameter of the microcapillaries in thepolymeric coating can be at least 50 μm, at least 100 μm, or at least250 μm. Furthermore, the microcapillaries in the polymeric coating canhave an average diameter in the range of from 50 to 1,990 μm, from 50 to990 μm, from 50 to 890 μm, from 100 to 790 μm, from 150 to 690 μm, orfrom 250 to 590 μm. It should be noted that, despite the use of the termdiameter, the cross-section of the microcapillaries need not be round.Rather, they may take a variety of shapes, such as oblong as shown inFIGS. 4B and 4C. In such instances, the “diameter” shall be defined asthe longest dimension of the cross-section of the microcapillary. Thisdimension is illustrated as λ in FIG. 4B. The “average” diameter shallbe determined by taking three random cross-sections from a polymericcoating, measuring the diameter of each microcapillary therein, anddetermining the average of those measurements. The diameter measurementis conducted by cutting a cross section of the extruded article andobserving under an optical microscope fitted with a scale to measure thediameter of the micro-capillary.

In one or more embodiments, the ratio of the thickness of the polymericcoating to the average diameter of the microcapillaries can be in therange of from 2:1 to 400:1

The spacing of the microcapillaries can vary depending on the desiredproperties to be achieved. Additionally, the spacing of themicrocapillaries can be defined relative to the diameter of themicrocapillaries. For instance, in various embodiments, themicrocapillaries can be spaced apart a distance of less than 1 times theaverage diameter of the microcapillaries, and can be as high as 10 timesthe average diameter of the microcapillaries. In various embodiments,the microcapillaries can be spaced apart an average of 100 to 5,000 μm,an average of 200 to 1,000 μm, or an average of 100 to 500 μm. Themeasurement “spaced apart” shall be determined on an edge-to-edge basis,as illustrated by “s” in FIG. 2C.

In various embodiments, when the microcapillary material is anelastomer, the polymeric coating can have higher flexibility, especiallyat low temperature, and reduced density because of the presence of lowerdensity elastomer in the microcapillary.

Peelable Coating

In one or more embodiments, a coated conductor is provided having apeelable polymeric coating. In such embodiments, the peelable polymericcoating comprises a polymeric matrix material and in the range of from 1to 8 of the above-described microcapillaries which extend substantiallyin the direction of elongation of the peelable polymeric coating. Invarious embodiments, the peelable polymeric coating comprises from 1 to6 microcapillaries, from 1 to 4 microcapillaries, or from 2 to 4microcapillaries. In various embodiments, the peelable polymeric coatingcomprises two microcapillaries. In other embodiments, the peelablepolymeric coating comprises three microcapillaries. In still otherembodiments, the peelable polymeric coating comprises fourmicrocapillaries.

In various embodiments, the microcapillaries can be spaced equidistantlyor substantially equidistantly radially around the peelable polymericcoating. For instance, when viewing a cross-section of the peelablepolymeric coating taken orthogonal to the direction of elongation of themicrocapillaries, if the peelable polymeric coating contains only twomicrocapillaries, they can be spaced about 180° apart from one another;if the peelable polymeric coating contains three microcapillaries, theycan be spaced about 120° apart from one another; or if the peelablepolymeric coating contains four microcapillaries, they can be spacedabout 90° apart from one another. In other embodiments, and regardlessof their radial placement, when viewed as a cross section takenorthogonal to the direction of their elongation, the microcapillariesmay be placed at different positions across the thickness of thecoating, for examples in sets of two or more capillaries, on top or inclose vicinity to one another and separated by a solid wall of thematrix material.

The microcapillaries of the peelable polymeric coating can (i) defineindividual, discrete void spaces; (ii) comprise an elastomeric polymerhaving a lower flexural modulus than the polymeric matrix material;(iii) comprise a non-polymeric, low-viscosity filler material capable ofbeing pumped into the microcapillaries; or (iv) combinations of two ormore of (i)-(iii).

Whether the microcapillaries are filled or void, the microcapillariescan be completely surrounded by the polymeric matrix material whenviewed as a cross-section taken orthogonal to the direction ofelongation of the microcapillaries. In various embodiments, theaggregate of the space defined by the microcapillaries when viewed inthe cross-section can be less than 20 area percent (“area %”), less than15 area %, less than 10 area %, or less than 5 area % of the total areaof the peelable polymeric coating cross-section. In such embodiments,the aggregate of space defined by the microcapillaries when viewed inthe cross-section can be at least 0.05 area %, at least 0.1 area %, atleast 0.5 area %, at least 1 area %, or at least 2 area % of the totalarea of the peelable polymeric coating cross-section.

As noted above, in various embodiments, the microcapillaries can defineindividual, discrete void spaces. In such embodiments, themicrocapillaries can be filled with a microcapillary fluid that is a gasa room temperature, such as air.

As noted above, in various embodiments, the microcapillaries cancomprise an elastomeric polymer. In such embodiments, the elastomericpolymer has a lower flexural modulus than the polymeric matrix material,as described in greater detail below. Suitable elastomers include any ofthose described above, but may be limited due to the type of polymericmatrix material selected. In various embodiments, the elastomericpolymer can be selected from the group consisting of an olefinelastomer, a silicone elastomer, a urethane elastomer, an amorphousrubber, and combinations of two or more thereof.

As just noted, one or more embodiments of the present inventioncontemplate a peelable polymeric coating having a relativelyhigh-modulus polymeric matrix material and a relatively low-moduluspolymeric microcapillary material, where the flexural modulus of thepolymeric matrix material is high relative to the polymericmicrocapillary material and the flexural modulus of the polymericmicrocapillary material is low relative to the polymeric matrixmaterial. Generally, the high-modulus polymeric matrix material can havea flexural modulus of at least 300,000 psi, or in the range of from300,000 to 800,000 psi, from 325,000 to 700,000 psi, or from 330,000 to600,000 psi. By way of example, a typical flexural modulus forpoly(p-phenylene sulfide) (“PPS”) is about 600,000 psi, forpolyether-ether-ketone is about 590,000 psi, for polycarbonate is about345,000 psi, for polyethylene terephthalate is about 400,000 psi, forpolybutylene terephthalate is about 330,000 psi, and for nylon 6/6 isabout 400,000 psi (all unfilled).

The high-modulus polymers are generally known as high-performancepolymers exhibiting high heat resistance (as measured by the heatdeflection temperature for example), excellent mechanical properties, aswell as abrasion and chemical resistance properties. They are, however,typically higher density polymers, having densities generally greaterthan 1.3 g/cm³. In various embodiments, the high-modulus polymers of thepolymeric matrix material can comprise polybutylene terephthalate(“PBT”), polyethylene terephthalate (“PET”), a polycarbonate, apolyamide (e.g., a nylon), polyether-ether-ketone (“PEEK), orcombinations of two or more thereof. In an embodiment, the polymericmatrix material comprises PBT.

The low-modulus polymeric microcapillary material can have a flexuralmodulus of less than 250,000 psi, or in the range of from 100 to 250,000psi, or from 500 to 200,000 psi. By way of example, a typicalhigh-density polyethylene has a flexural modulus of about 200,000 psi, atypical low-density polyethylene has a flexural modulus of about 30,000psi, a typical thermoplastic polyurethane has a flexural modulus ofabout 10,000 psi, and a typical polyolefin elastomer (e.g., ENGAGE™8402) has a flexural modulus of about 580 psi.

The low-modulus materials are generally characterized by highflexibility and excellent impact resistance, even at low temperatures.These resins can have a melt index ranging from less than 1.0 to greaterthan 1,000 g/10 minutes such as, for example, AFFINITY™ GA grades ofolefin elastomer, commercially available from The Dow Chemical Company.These polyolefin elastomer resins can also have a density as low as0.857 g/cm³ and a melting point as low as 38° C. such as ENGAGE™ 8842also from The Dow Chemical Company.

In one or more embodiments, the polymeric microcapillary material cancomprise any of the ethylene-based polymers described above (e.g., HDPE,LDPE, EEA, EVA); olefin elastomers (such as described above) and otherethylene copolymers such as AFFINITY™, ENGAGE™, and VERSIFY™ copolymers,commercially available from The Dow Chemical Company; olefin blockcopolymers (such as those commercially available under the trade nameINFUSE™ from The Dow Chemical Company, Midland, Mich., USA),mesophase-separated olefin multi-block interpolymers (such as describedin U.S. Pat. No. 7,947,793), olefin block composites (such as describedin U.S. Patent Application Publication No. 2008/0269412, published onOct. 30, 2008), or combinations of two or more thereof.

As noted above, in various embodiments, the microcapillaries cancomprise a low-viscosity filler material capable of being pumped intothe microcapillaries. In other words, such low-viscosity filler materialcan be incorporated into the microcapillaries following extrusion of thepeelable polymeric coating; such fillers are not required to beco-extruded with the polymeric matrix material. This is in contrast withpolymeric materials, such as the elastomers discussed above.

Suitable low-viscosity fillers include fluids with a broad range inviscosity, as shown in Table 1. As used herein, “low-viscosity” shalldenote liquid fillers (at 100° C.) that have a kinematic viscosity at100° C. in the range of from 1 to 45,000 centistokes (“cSt”). In variousembodiments, the low-viscosity filler can have a viscosity at 100° C. inthe range of from 4 to 30,000 cSt, from 4 to 15,000 cSt, from 4 to 2,000cSt, from 4 to 1,700 cSt, or from 4 to 250 cSt. Specific examples ofsuch materials include paraffinic oils, such as the SUNPAR™ grades(available from Sunoco Corp.); vegetable oils, such as soybean oil,poly-alpha olefin (“PAO”) fluids, such as the DURASYN™ grades (availablefrom Ineos Corp.); and polybutenes, such as the INDOPOL™ grades(available from Ineos Corp.).

Other suitable materials are formulated compounds such as thosetypically used in filling and flooding telecommunication cables. Anexample of a filling compound used in buffer tube fiber optictelecommunication cables is a thixotropic gel, disclosed in U.S. Pat.No. 5,505,773 and composed of polybutylene, fumed silica, andpolyethylene wax. A typical flooding compound is disclosed in U.S. Pat.No. 4,724,277 and is composed of a mixture of microcrystalline wax, apolyethylene, and a rubber. Examples of such materials include thosecommercially available from Sonneborn LLC, Soltex Corp, H&R ChemPharm(UK) Ltd, and MasterChem Solutions; as well as compounds based on highmelt index Polyolefin Elastomers such as those disclosed in U.S.Provisional Patent Application Ser. Nos. 62/140,673 and 62/140,677. Somecable filling/flooding compounds are engineered with viscosityexhibiting shear thinning profiles to enable pumping at room temperaturewithout requiring additional heating.

TABLE 1 Typical viscosities of suitable low viscosity materials Temper-Kinematic Viscosity (cSt) ature (Typical Range) Material (° C.) Min.Max. Ref. Lubricating Oil (SAE 100 4 25 1 Engine Oil) Lubricating Oil(SAE 100 7 1,700 1 Gear Oil) Vegetable Oils 100 6 15 2-3 Polybutene 1001 45,000 4 Sunpar Oil 100 3 31 5 Cable Flooding 120 200 250 6 Compounds150 170 7 1 J. Sanders, Putting the Simple Back into Viscosity, WhitePaper, Lubrication Engineers Inc., 2011 2 T. W. Ryan et al., The Effectsof Vegetable Oil Properties on Injection and Combustion in Two DifferentDiesel Engines, Journal of the American Oil Chemists' Society 61, no. 10(October 5): 1610-1619 3 Noureddini H. et al., Viscosities of VegetableOils and Fatty Acids, Journal of the American Oil Chemists' Society 69,no. 12 (December 1): 1189-1191 4 Indopol Polybutene Product Bulletin,Ineos Oligomers, Brochure No. PB1000, November 2009 5 Sunoco ProductInformation, Sunpar Range, March 2013 6 Telephone Flooding Compound FC57 M, Product Data Sheet, Sonneborn Refined products, March 2012 7 CableFlooding Compounds (Soltex Flood 522), Soltex, March 2009

The microcapillaries in the peelable polymeric coatings can either belongitudinally continuous (or substantially continuous) ornon-continuous along the length of the polymeric coating. As used inthis embodiment, the term “substantially continuous” shall mean that themicrocapillaries extend in an uninterrupted fashion for at least 90% ofthe length of the peelable polymeric coating. When longitudinallydiscontinuous, the microcapillaries can have any desired length. Invarious embodiments, the longitudinally discontinuous microcapillariescan have an average length ranging from 1 to about 100 cm, from 1 to 50cm, from 1 to 20 cm, from 1 to 10 cm, or from 1 to 5 cm.

In various embodiments, the peelable polymeric coatings can compriseexternal indicia corresponding to the location of the microcapillaries.Such external indicia should enable a person working with the coatedconductor to locate the points on the coating that enable the coating tobe peeled. Incorporation of external indicia can be accomplished by anymeans known or hereafter discovered in the art. Examples of such indiciainclude, but are not limited to, printing, engraving, coloring, orembossing.

In one or more embodiments, the peelable polymeric coating can have areduction in tensile strength of less than 50%, less than 45%, less than40%, less than 35%, or less than 30% relative to an identical coatingprepared from the same polymeric matrix material except not havingmicrocapillaries. Additionally, the peelable polymeric coating can havea reduction in tensile strength in the range of from 10 to 50%, or from20 to 45% relative to an identical coating prepared from the samepolymeric matrix material except not having microcapillaries.

In various embodiments, the peelable polymeric coating can have areduction in elongation-at-break of less than 30%, or less than 25%relative to an identical coating prepared from the same polymeric matrixmaterial except not having microcapillaries. Reduction inelongation-at-break is determined by calculating the difference inelongation-at-break between the reference coating and the peelablecoating, dividing that difference by the elongation-at-break of thereference coating, and multiplying by 100%. For example, if a referencecoating has an elongation-at-break of 900%, and a peelable coating hasan elongation-at-break of 800%, the reduction in elongation at break is(100/900)*100%, or 11.1%. Additionally, the peelable polymeric coatingcan have a reduction in elongation-at-break in the range of from 5 to30%, or from 10 to 25% relative to an identical coating prepared fromthe same polymeric matrix material except not having microcapillaries.

In various embodiments, the peelable polymeric coating can have areduction in tear strength of at least 5%, at least 10%, at least 25%,at least 50%, or at least 75% relative to an identical coating preparedfrom the same polymeric matrix material except not havingmicrocapillaries. Additionally, the peelable polymeric coating can havea reduction in tear strength up to 90%, up to 85%, or up to 80% relativeto an identical coating prepared from the same polymeric matrix materialexcept not having microcapillaries.

Preparation of the peelable coatings can be accomplished by simplemodifications of the above-described die assemblies to reduce the numberof microcapillaries as desired. Such modifications are within theabilities of one having ordinary skill in the art.

Test Methods

Density

Density is determined according to ASTM D 792.

Melt Index

Melt index, or I₂, is measured in accordance with ASTM D 1238, condition190° C./2.16 kg, and is reported in grams eluted per 10 minutes.

Tensile Strength and Elongation at Break

Measure tensile strength and elongation according to ASTM method D 638.

Tear Strength

The tear strength is measured as follows: 5.0-inch-long specimens aredie cut from extruded tape samples and a 1.0-inch-long slit is made oneach specimen. Tear testing is conducted on an Instron Model 4201 testerin the axial tape direction at 12″/min speed. Reported data are averagevalues based on measurement of five specimens.

Materials

The following materials are employed in the Examples, below.

AXELERON™ GP C-0588 BK (“LDPE”) is a low-density polyethylene having adensity of 0.932 g/cm³, a melt index (I₂) in the range of from 0.2 to0.4 g/10 min., and containing carbon black in an amount ranging from2.35 to 2.85 wt % (ASTM D1603). AXELERON™ GP C-0588 BK is commerciallyavailable from The Dow Chemical Company, Midland, Mich., USA.

AXELERON™ FO 6548 BK (“MDPE”) is a medium-density polyethylene having adensity of 0.944 g/cm³, a melt index (I₂) in the range of from 0.6 to0.9 g/10 min., and containing carbon black in an amount ranging from2.35 to 2.85 wt % (ASTM D1603). AXELERON™ FO 6548 BK is commerciallyavailable from The Dow Chemical Company, Midland, Mich., USA.

ENGAGE™ 8200 is an ethylene/octene polyolefin elastomer having a densityof 0.870 g/cm³ and a melt index of 5.0 g/10 min., which is commerciallyavailable from The Dow Chemical Company, Midland, Mich., USA.

EXAMPLES

Sample Preparation

Air-Filled Microcapillary Samples

Prepare four samples (S1-S4) using a tape-extrusion system consisting ofa single-screw extruder (3.81-cm Killion extruder) fitted with amicrocapillary die capable of handling a polymer melt and an air stream,as schematically depicted in FIG. 1. The die to be used in theseExamples is described in detail in PCT Published Patent Application No.WO 2014/003761, specifically with respect to FIGS. 4A and 4A1, and thecorresponding text of the written description, which is incorporatedherein by reference. The die has 42 microcapillary nozzles, a width of 5cm, and a die gap of 1.5 mm. Each microcapillary nozzle has an outerdiameter of 0.38 mm and an inner diameter of 0.19 mm. The plant air issupplied by an air line with a flow meter, which is fully open prior toheating the machine to prevent blockage of the microcapillary nozzles bythe backflow of polymer melt. In preparing the microcapillary sheets,first the extruder, gear pump, transfer lines, and die are heated to theoperating temperatures with a “soak” time of about 30 minutes. Operatingtemperatures are shown in Table 2. As the polymer pellets pass throughthe extruder screw, the polymer becomes molten. The extruder screw feedsthe polymer melt to the gear pump, which maintains a substantiallyconstant flow of polymer melt towards the microcapillary die. Next, thepolymer melt passes over the microcapillary nozzles and meets withstreamlines of air flow, which maintain the size and shape of themicrocapillary channels. Upon exiting the extrusion die, the extrudateis passed over a chill roll. Once the extrudate is quenched, it is takenby a nip roll. The air flow rate is carefully adjusted in such a waythat the microcapillaries do not blow out but maintain reasonablemicrocapillary dimensions. The line speed is controlled by a nip roll inthe rollstack. The sample compositions, their properties, and otherprocess parameters are provided in Table 3, below.

TABLE 2 Temperature Profile of Microcapillary Extrusion Line forAir-Filled Microcapillary Sheets. Extruder Extruder Extruder ExtruderAdaptor Transfer Screen Feed Die Zone 1 Zone 2 Zone 3 Zone 4 Zone LineChanger block Zone (° F.) (° F.) (° F.) (° F.) (° F.) (° F.) (° F.) (°F.) (° F.) 374 392 410 428 428 428 428 428 428The resulting tapes are about 1.6 inches wide and approximately 50 milsthick, and have the following properties, shown in Table 3.

TABLE 3 Composition and Properties of Samples S1-S4 S1 S2 S3 S4 MDPE (wt%) 100 100 — — LDPE (wt %) — — 100 100 Air Flow Rate (mL/min) 20 40 2040 Line Speed (ft/min) 6.6 7.2 6.0 6.0 Average Film Thickness (mm) 1.001.06 1.04 1.21 Average Film Width (cm) 4.1 4.1 4.2 4.2 Area Percentageof 27.5 35 22.5 31.2 Microcapillaries in the Film (%) Long Axis of aMicrocapillary 718 769 722 804 (μm) Short Axis of a Microcapillary 389504 355 519 (μm) Space between Two 263 210 264 196 Microcapillaries (μm)Film Surface to Inner Surface of 282 279 330 352 Microcapillary (μm)Comparative Samples and Elastomer-Filled Microcapillary Sample

Prepare one Sample (S5) and two Comparative Sample (CS1 and CS2) using atape-extrusion system consisting of two single-screw extruders (1.9-cmand 3.81-cm Killion extruders) fitted with a microcapillary die capableof handling two polymer melt streams. This line consists of a 3.81-cmKillion single-screw extruder to supply polymer melt for the matrixmaterial and a 1.9-cm Killion single-screw extruder to supply polymermelt for the microcapillaries via a transfer line to the microcapillarydie. The die to be used in these Examples is described in detail in PCTPublished Patent Application No. WO 2014/003761, specifically withrespect to FIGS. 4A and 4A1, and the corresponding text of the writtendescription, which is incorporated herein by reference. The die has 42microcapillary nozzles, a width of 5 cm, and a die gap of 1.5 mm. Eachmicrocapillary nozzle has an outer diameter of 0.38 mm and an innerdiameter of 0.19 mm.

Sample S5 and Comparative Samples CS1 and CS2 are prepared as follows.First, the extruders, gear pump, transfer lines, and die are heated tothe operating temperatures with a “soak” time of about 30 minutes. Thetemperature profiles for the 3.81-cm and 1.9-cm Killion single-screwextruders are given in Table 4, below. Microcapillary polymer resins arecharged into the hopper of the 1.9-cm Killion single-screw extruder, andthe screw speed is turned up to the target value (30 rpm). As thepolymer melt exits the microcapillary nozzles, the matrix polymer resinsare filled into the hopper of 3.81-cm Killion single-screw extruder andthe main extruder is turned on. The extruder screw of the 3.81-cmKillion single-screw extruder feeds the melt to a gear pump, whichmaintains a substantially constant flow of melt towards themicrocapillary die. Then, the polymer melt from the 3.81-cm Killionsingle-screw extruder is divided into two streams, which meet withpolymer strands from microcapillary nozzles. Upon exiting the extrusiondie, the extrudate is cooled on a chill roll on a rollstack. Once theextrudate is quenched, it is taken by a nip roll. The line speed iscontrolled by a nip roll in the rollstack.

TABLE 4 Temperature Profiles of the 3.81-cm and 1.9-cm KillionSingle-Screw Extruders Extruder Extruder Extruder Extruder AdaptorTransfer Screen Feed Die Zone 1 Zone 2 Zone 3 Zone 4 Zone Line Changerblock Zone Extruders (° F.) (° F.) (° F.) (° F.) (° F.) (° F.) (° F.) (°F.) (° F.) 3.81-cm 374 392 410 428 428 428 428 428 428 Extruder 1.9-cm338 410 428 — — 428 — — — Extruder

The extrusion system is set up to supply two polymer melt streams: afirst polymer (3.81-cm Killion extruder) to make a continuous matrixsurrounding a second polymer (1.9-cm Killion extruder) shaped asmicrocapillaries embedded in the first polymer. The first polymer(matrix) of S5 is MDPE, and the second polymer (microcapillary) of S5 isENGAGE™ 8200. For CS1, both the first and second polymers are MDPE. ForCS2, both the first and second polymers are LDPE. The processingconditions and microcapillary dimension for S5, CS1, and CS2 are givenin Table 5, below. Estimated from density measurements, S5 contains 18weight percent of the microcapillary material (ENGAGE™ 8200).

TABLE 5 Processing Conditions and Microcapillary Dimensions for S1 andCS1 S5 CS1 CS2 Matrix Material MDPE MDPE LDPE Microcapillary MaterialENGAGE ™ 8200 MDPE LDPE Screw Speed of 3.81-cm 15 15 15 Extruder (rpm)Screw Speed of 1.9-cm 30 30 30 Extruder (rpm) Line Speed (ft/min) 5 5 5Average Film Thickness (mm) 1.30 1.05 1.1 Average Film Width (cm) 4.24.5 4.4 Area Percentage of 17.4 — — Microcapillaries in the Film (%)Long Axis of a Microcapillary 604 — — (μm) Short Axis of aMicrocapillary 355 — — (μm) Space between Two 371 — — Microcapillaries(μm) Film Surface to Inner Surface of 354 — — Microcapillary (μm)

EXAMPLE

Analyze each of CS1, CS2, and S1-S5 according to the Test Methodsprovided above. The results are provided in Table 6, below.

TABLE 6 Properties of CS1, CS2, and S1-S5 Tear % Tear Tensile TensileStrength Reduction Strength Elongation Sample (lb/in.) vs. Control (psi)(%) MDPE-based Samples CS1 839.3 — 4,666 910 S1 197.3 76.5 3,168 807 S2167.3 80.1 2,530 693 S5 413.4 50.7 3,388 857 LDPE-based Samples CS2295.7 — 2,836 661 S3 128.1 56.7 2,203 523 S4 83.1 71.9 2,040 598

CS1 is a sample representing a solid tape made of commercial MDPE, whichshows a tear strength of about 840 lb/in. and the typical tensile andelongation properties for this compound. S1 and S2 show the samecompound extruded into a tape with air-filled microcapillaries. Whentorn in the axial direction along one of the capillaries, the tearstrength is shown to be reduced by 76 and 80% respectively depending onthe size of the microcapillaries. S5 shows that a sample havingmicrocapillaries filled with a polyolefin elastomer (ENGAGE™ 8200) canalso provide significant reduction in tear strength (about 51%).

CS2 is a sample representing a solid tape made of commercial LDPE, whichshows a tear strength of about 296 lb/in. and the typical tensile andelongation properties for this compound. S3 and S4 are samples madeusing the LDPE compound with air-filled microcapillaries, showing tearstrength reductions of about 57 and 72% respectively depending on thesize of the microcapillaries.

It should be noted that all the inventive samples above are made with 42microcapillaries. Such a construction has an effect on the overalltensile and elongation properties as shown by the data. As describedearlier, however, only a limited number (e.g., 2 to 4) ofmicrocapillaries placed around the jacket circumference would be neededto provide ease of tearing, while the rest of the jacket can remainunchanged for maximum mechanical protection of the cable. This wouldminimize the negative impact of the microcapillaries on the overalljacket mechanical properties.

The invention claimed is:
 1. A coated conductor, comprising: (a) aconductor that is a cable or an optical fiber; and (b) an annularmicrocapillary product that is a peelable polymeric coating extrudedonto and completely surrounding the conductor, wherein said peelablepolymeric coating comprises a polymeric matrix material and in the rangeof from 1 to 8 microcapillaries which extend substantially in thedirection of elongation of said peelable polymeric coating, wherein saidmicrocapillaries define individual, discrete void spaces, and saidmicrocapillaries are completely surrounded by the polymeric matrixmaterial.
 2. The coated conductor of claim 1, wherein saidmicrocapillaries contain air within one or more of said void spaces. 3.The coated conductor of claim 1, wherein an aggregate of the spacedefined by said microcapillaries when viewed as a cross-section of thepeelable polymeric coating taken orthogonal to the direction ofelongation of said microcapillaries constitutes less than 20 areapercent of the total area of said peelable polymeric coatingcross-section.
 4. The coated conductor of claim 1, wherein saidmicrocapillaries have an average diameter in the range of from 0.5 μm to2,000 μm, wherein said microcapillaries have a cross-sectional shapeselected from the group consisting of circular, rectangular, oval, star,diamond, triangular, square, pentagonal, hexagonal, octagonal,curvilinear, and combinations thereof, wherein said peelable polymericcoating has a thickness in the range of from 10 to 180 mils.
 5. Thecoated conductor of claim 1, wherein the ratio of the thickness of saidpeelable polymeric coating to the average diameter of saidmicrocapillaries is in the range of from 2:1 to 400:1.
 6. The coatedconductor of claim 1, wherein said peelable polymeric coating has areduction in tensile strength of less than 50% relative to an identicalcoating prepared from the same matrix material except not havingmicrocapillaries, wherein said peelable polymeric coating has areduction in elongation-at-break of less than 30% relative to anidentical coating prepared from the same matrix material except nothaving microcapillaries.
 7. The coated conductor of claim 1, whereinsaid polymeric matrix material comprises an ethylene-based polymer. 8.The coated conductor of claim 1, wherein said peelable polymeric coatingcomprises external indicia corresponding to the internal location ofsaid microcapillaries.
 9. The coated conductor of claim 1, wherein saidmicrocapillaries are substantially longitudinally continuous along thelength of said peelable polymeric coating.
 10. The coated conductor ofclaim 1, wherein said microcapillaries are longitudinally discontinuousalong the length of said peelable polymeric coating.
 11. The coatedconductor of claim 1 wherein the individual, discrete void spacesconsist of air.
 12. The coated conductor of claim 1, wherein theindividual discrete void spaces consist of air.
 13. The coated conductorof claim 1 wherein the conductor has a direction of elongation; and themicrocapillaries extend in the same direction of elongation as theconductor.
 14. The coated conductor of claim 13, wherein each discretevoid space consists of a gas.
 15. The coated conductor of claim 14,wherein each discrete void space consists of air.
 16. The coatedconductor of claim 15, wherein each microcapillary is substantiallycontinuous along the length of the peelable polymeric coating.
 17. Thecoated conductor of claim 15, wherein each microcapillary islongitudinally discontinuous along the length of the peelable polymericcoating.